Enabled the Travis multi-OS feature so that we have an OS X build as well.
Enabled the Travis multi-OS feature so that we have an OS X build as well.

Signed-off-by: Dimitar Dobrev <ca751a5c976abad79158718440750fc638d19ebc@yahoo.com>

zillemarco/CppSharp,ktopouzi/CppSharp,zillemarco/CppSharp,mydogisbox/CppSharp,genuinelucifer/CppSharp,u255436/CppSharp,SonyaSa/CppSharp,u255436/CppSharp,mohtamohit/CppSharp,mohtamohit/CppSharp,ktopouzi/CppSharp,u255436/CppSharp,zillemarco/CppSharp,zillemarco/CppSharp,mono/CppSharp,mono/CppSharp,mono/CppSharp,ktopouzi/CppSharp,SonyaSa/CppSharp,zillemarco/CppSharp,ddobrev/CppSharp,SonyaSa/CppSharp,ktopouzi/CppSharp,mydogisbox/CppSharp,mohtamohit/CppSharp,ktopouzi/CppSharp,mydogisbox/CppSharp,genuinelucifer/CppSharp,mohtamohit/CppSharp,genuinelucifer/CppSharp,mono/CppSharp,inordertotest/CppSharp,inordertotest/CppSharp,mono/CppSharp,inordertotest/CppSharp,SonyaSa/CppSharp,mono/CppSharp,mohtamohit/CppSharp,inordertotest/CppSharp,ddobrev/CppSharp,mydogisbox/CppSharp,ddobrev/CppSharp,u255436/CppSharp,SonyaSa/CppSharp,u255436/CppSharp,mydogisbox/CppSharp,ddobrev/CppSharp,ddobrev/CppSharp,genuinelucifer/CppSharp,genuinelucifer/CppSharp,inordertotest/CppSharp